Combined magnetic suspension and transformer



Aug. 10, 1965 H. E. CLARK 3,199,932

COMBINED MAGNETIC SUSPENSION AND TRANSFORMER Filed March 1, 1962 INVENTOR.

zQ'a/glt fv- United States Patent 3,199,932 COMBINED MAGNETIC SUSPENSION AND TRANSFURMER Harold E. Clark, Middleton, Mass, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. 1, 1962, Ser. No. 176,550 4 Claims. (Cl. 308) This invention relates to a transformer in combination with an apparatus for magnetically suspending a body and with means for providing electrical power to the body without the use of flexible leads.

It is often desirable in applications wherein a body is magnetically suspended to provide electrical power to the suspended body, such as for energizing windings of a motor mounted within the suspended body. Flexible mechanical leads could be used for supplying the electrical power to the suspended body; however, such leads might limit angular excursion of the suspended body and exert reaction torques acting on the suspended body.

In accordance with this invention, electrical power is provided to a magnetically suspended body without the use of flexible mechanical leads. This is accomplished by magnetically suspending a body between two electro-' magnets each excited by AC. voltage. A secondary winding is provided on the suspended body whereby voltage is induced in the winding due to the magnetic field generated by one of the electromagnets and related in phase to the voltage exciting the electromagnet. Accordingly, AC. voltage is provided to the suspended body.

A more complete understanding of this invention may be had from the detailed description which follows taken in conjunction with the drawing shown in the single figure illustrating a plan view partly in section of one embodiment of the invention.

Referring now to the single figure there is shown an illustrative embodiment of the invention. A cylindrically shaped hollow body 10 which may take the form of a gyroscope float is magnetically suspended within a cylindrically shaped hollow casing 12 between two coaxially disposed electromagnets 14 and 16. A viscous fluid 13 fills the spacing between the body 10 and the casing 12 so as to provide a degree of buoyancy for the body 10 as well as viscous damping. The electromagnet 14 comprises a cylindrically shaped magnet pole piece 18 mounted on a ferrite cup 26 suitably secured to the casing 12 and an electromagnet coil 22 mounted in an annular groove 24 in the cup 26. The electromagnet 16 comprises a cylindrically shaped magnetic polepiece 26 mounted on a ferrite cup 28 suitably secured to the casing 12 and an electromagnet coil 30 mounted in an annular groove 31 in the cup 28. The body 10 has mounted thereon two coaxially disposed ferrite cups 32 and 34 having respectively mounted thereon cylindrically shaped magnetic armatures 36 and 38. Secondary windings 4i and 42 are respectively mounted in annular grooves 44 and 48 in the cups 32 and 34, respectively. A gimbal assembly 50 is mounted with the inner side of the casing 16 and supports a two-phase motor 52 which is provided for rotatably driving an inertial element within the casing 10. The secondary winding 40 is electrically connected with terminals 54 and 56 on the motor 52 and the secondary winding 42 is electrically connected with the terminals 58 and 60 on the motor 52. Each of the electromagnet coils 22 and 30 are connected across a diiferent phase of a constant voltage two phase AC. voltage source 62.

The voltage source 62 provides alternating current flow in the coils 22 and 30 of the electromagnets 14 and 16, respectively, creating magnetic forces which act on the body 10 to support it. The magnetic flux created by "ice the electromagnet 14 flows as follows: from the pole piece 18 across a gap 66, the armature 36, the ferrite cup 32, across the gap 66, the ferrite cup 26 and back to the pole piece 18. Similarly the magnetic flux created by the electromagnet 16 flows as follows: from the pole piece 26 across a gap 68, the armature 38, the ferrite cup 34, across the gap 68, the ferrite cup 28 and back to the pole piece 26.

If the body 113 is axially displaced there will result a change in length of gaps 66 and 68 between the pole piece 18 and the armature 36 and the pole piece 26 and the armature 38, respectively, resulting in a change in the reluctance of the flux path of each gap. This will result in a change in inductance of the coil of each electromagnet causing the current flowing therein to change and thus in turn causing a change in the attractive magnetic forces between the electromagnets and the armatures. For example, if the body 10 is axially displaced to the left in the single figure, the length of gap 66 will decrease and the length of gap 68 will increase. Thus the reluctance of the flux path in the gap 66 will decrease resulting in an increase in the inductance of coil 22 whereas the reluctance of the fiux path in the gap 68 will increase resulting in a decrease in the inductance of coil 3% Since constant alternating voltage from source 62 is applied across the coils 22 and 30 the current flowing in coil 22 will decrease and the current flowing in coil 30 will increase. Hence the magnetometive force created by the current flowing in coil 22'will decrease and the magnetomotive force created by the current flowing in coil 30 will increase resulting in a net axial magnetic force acting on the body 10 so as to axially recenter it between the electromagnets 14 and 16.

If the body 10 is displaced radially of its axis of symmetry with respect to the electromagnets 14 and 16 there will result a decrease in overlapping area between the pole piece 18 and the armature 36 and between the pole piece 26 and the armature 38 whereby the flux lines will crowd together in the areas of minimum reluctance. Since the electromagnets 14 and 16 are excited by constant alternating voltage from source 62 such changes in reluctance will result in forces being set up so as to act on the armatures 36 and 33 in a direction to decrease the reluctance and increase the permeance of gaps 66 and 63, respectively. Thus, the armatures will be moved toward the configuration of minimum reluctance so as to radially recenter the body 10 with respect to the pole pieces 18 and 26 of the electromagnets 14 and 16, respectively.

Whereas the embodiment of the invention shown in the single figure has been described with respect to a particular magnetic suspension means as described above other arrangements for providing radial and axial magnetic suspension of the body 10 may be used. One such arrangement may take the form of the magnetic suspension system described in U.S. Patent No. 3,146,038, issued August 25, 1964.

In accordance with the present invention, voltages will be induced in the secondary windings 40 and 42 related in phase to the voltages exciting the electromagnet coils 22 and 30, respectively. For example, the magnetic flux created by the electromagnet 14 will link the secondary winding 46 inducing a voltage therein related in phase to the voltage applied to the electromagnet coil 22 from the two phase voltage source 62. Similarly, a voltage will be induced in the secondary winding 42 related in phase to the voltage applied to the electromagnet coil 30 from the two phase voltage source 62. Hence, two phase voltage may be obtained from the secondary windings 4t) and 42 and applied to terminals 54 and 56 and 5S and 6t) so as to excite the two phase motor 52.

Although the description of this invention has been given with respect to a particular embodiment, it is not to be construed in a limiting sense. Numerous variations and modifications within the spirit and scope of the invention will now occur to those skilled in the art. For a definition of the invention, reference is made to the appended claims.

I claim:

1. The combination of a magnetic suspension system and power supply transformer for a body which is rotatable about a predetermined axis comprising first and second electromagnets, the electromagnets including respective coils disposed normal to and coaxial with the predetermined axis, a body freely suspended between the electromagnets and including first and second magnetic armatures disposed in magnetic proximity to the first and second electromagnets respectively, a source of alternating voltage connected with each electromagnet for excitation thereof whereby the body is suspended by the attractive magnetic forces between the armatures and the respective electromagnets, a secondary coil disposed on the body coaxially adjacent one of the electromagnet coils and spaced therefrom, means to define a magnetic circuit between said one electromagnet coil and the secondary coil thereby to transfer electrical energy between the coils, electrical load means carried by the body, and output circuit means connecting the secondary coil with the electrical load for energization thereof.

2. The combination of a magnetic suspension system for a body which is adapted for rotation about a predetermined axis, and power supply transformer for an electrical load carried by the body comprising first and second electromagnets, the electromagnets including respective coils disposed normal to and coaxial with the predetermined axis, a freely suspended body having first and second coaxially disposed magnetic armatures mounted thereon and disposed in magnetic proximity the first and second electromagnets respectively, each electromagnet comprising a magnetic pole piece mounted on supporting means and having a coil wound thereon, each coil connected to receive a different phase of a two-phase alternating voltage source for excitation thereby to suspend the body by the attractive magnetic forces between the first electromagnet and the first armature and between the second electromagnet and the second armature, first and second windings wound on the first and second armatures, respectively, coaxially adjacent the first and second electromagnet coils and spaced therefrom by a gap, respective means disposed adjacent the armatures and pole pieces for defining a low reluctance magnetic circuit between each of the coils and the coaxially adjacent windings thereby to transfer electrical energy therebetween, an electric load device carried by the body, and output circuit means connecting the load device with windings for excitation thereof.

3. The combination of a magnetic suspension system for a body which is adapted for rotation about a predetermined axis, and power supply transformer for an electrical load carried by the body comprising first and second electromagnets, the electromagnets including respective coils disposed normal to and coaxial with the predetermined axis, a freely suspended hollow body having first and second coaxially disposed magnetic armatures mounted thereon and disposed in magnetic proximity to the first and second electromagnets respectively, each electromagnet comprising a magnetic pole piece mounted on supporting means and having a coil wound thereon, each coil connected to receive a different phase of a two-phase alternating voltage source for excitation to suspend whereby the body by the attractive magnetic forces between the first electromagnet and the first armature and between the second electromagnet and the second armature, first and second windings wound on the first and second armatures, respectively, coaxially adjacent the first and second electromagnet coils and spaced therefrom by a gap, respective means disposed adjacent the armatures and pole pieces for defining a low reluctance magnetic circuit between each of the coils and the coaxially adjacent windings thereby to transfer electrical energy therebetween, and a twophase motor mounted within the body electrically connected with the first and second windings and responsive to the voltages induced therein.

4. A system for suspending a gyro float assembly carrying an electrical load device comprising a housing, a gyro assembly disposed within the housing and rotatable about a predetermined axis, first and second electromagnets disposed on the predetermined axis at opposite ends of the housing and including first and second primary coils, first and second armature means disposed on the axis at opposite ends of the gyro assembly and in magnetic proximity to the first and second electromagnets respectively, a power source for energizing the electromagnets thereby to provide axial restraining forces between the electromagnets and the armature means for supporting the gyro assembly out of contact with the housing, first and second secondary coils mounted on the first and second armature means respectively, the secondary coils being coaxially disposed adjacent the primary coils and separated therefrom by respective gaps, an electrical load device carried by the gyro assembly and circuit means connecting the secondary windings to the load for excitation thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,809,526 10/57 Lundberg 30810 2,822,694 2/58 McKenney 30810 2,828,627 4/58 Gabrielson 745 3,079,574 2/63 Garcia 3081Q MILTON O. HIRSHFIELD, Primary Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noe 3,199,932 August 10, 1965 Harold E. Clark It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 45, for "magnet" read magnetic column 3, llne 38, after "proximity" insert to column 4, line 14, for "to suspend whereby" read thereby to suspend Signed and sealed this 19th day of July 1966.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. THE COMBINATION OF A MAGNETIC SUSPENSION SYSTEM AND POWER SUPPLY TRANSFORMER FOR A BODY WHICH IS ROTATABLE ABOUT A PREDETERMINED AXIS COMPRISING FIRST AND SECOND ELECTROMAGNETS, THE ELECTROMAGNETS INCLUDING RESPECTIVE COILS DISPOSED NORMAL TO AND COAXIAL WITH THE PREDETERMINED AXIS, A BODY FREELY SUSPENDED BETWEEN THE ELECTROMAGNETS AND INCLUDING FIRST AND SECOND MAGNETIC ARMATURES DISPOSED IN MAGNETIC PROXIMITY TO THE FIRST AND SECOND ELECTROMAGNETS RESPECTIVELY, A SOURCE OF ALTERNATING VOLTAGE CONNECTED WITH EACH ELECTROMAGNET FOR EXCITATION THEREOF WHEREBY THE BODY IS SUSPENDED BY THE ATTRACTIVE MAGNETIC FORCES BETWEEN THE ARMATURES AND THE RESPECTIVE ELECTROMAGNETS, A SECONDARY COIL DISPOSED ON THE BODY COAXIALLY ADJACENT ONE OF THE ELECTROMAGNET COILS AND SPACED THEREFROM, MEANS TO DEFINE A MAGNETIC CIRCUIT BETWEEN SAID ONE ELECTROMAGNET COIL AND THE SECONDARY COIL THEREBY TO TRANSFER ELECTRICAL ENERGY BETWEEN THE COILS, ELECTRICAL LOAD MEANS CARRIED BY THE BODY, AND OUTPUT CIRCUIT MEANS CONNECTING THE SECONDARY COIL WITH THE ELECTRICAL LOAD FOR ENERGIZATION. THEREOF. 